嵌入式 Linux 系统工程 034：栈、堆、malloc 与 mmap

#define _GNU_SOURCE
#include <assert.h>
#include <errno.h>
#include <fcntl.h>
#include <pthread.h>
#include <signal.h>
#include <stdint.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <sys/mman.h>
#include <sys/socket.h>
#include <sys/wait.h>
#include <time.h>
#include <unistd.h>

#define CHECK(x) do { if (!(x)) { fprintf(stderr, "check failed: %s at line %d (errno=%d)\n", #x, __LINE__, errno); exit(EXIT_FAILURE); } } while (0)

int main(void) {
    const size_t bytes = 1024 * 1024;
    unsigned char *p = mmap(NULL, bytes, PROT_READ | PROT_WRITE,
                           MAP_PRIVATE | MAP_ANONYMOUS, -1, 0);
    CHECK(p != MAP_FAILED);
    memset(p, 0x5a, bytes);
    CHECK(p[0] == 0x5a && p[bytes-1] == 0x5a);
    CHECK(munmap(p, bytes) == 0);
    puts("mapped, touched and unmapped 1 MiB; no RSS timing assumption");
    return 0;
}